C ++-MySQL连接器

Question

I'm using the c++ mysql connector to do operations in my mysql database.

My c++ program is a real time application (rest api) which is always running in the cloud, always waiting for user requests.

When i start my program for the first type i automatically create a connection to the database (the fields for the connector i load from a configuration file). Example:

conDataBase = new ConDatabase;
if (!conDataBase->Init()) return false;

The conDataBase is a global pointer accessible to all classes. The Init() function:

bool conDatabase::Init()
{
  GetParameterStr("DATABASE", "HOST", "", hostname, 255);
  db_hostname = hostname;
  GetParameterStr("DATABASE", "USER", "", user, 255);
  db_user = user;
  GetParameterStr("DATABASE", "PASSWORD", "", password, 255);
  db_password = password;
  GetParameterStr("DATABASE", "SCHEMA", "", schema, 255);
  db_schema = schema;
  printf("DATABASE: Connecting to %s \n",db_hostname.c_str());
  printf("DATABASE: Connecting at %s with user %s \n",db_schema.c_str(), db_user.c_str());

  try
  {
    driver = get_driver_instance();
    con = driver->connect(db_hostname.c_str(), db_user.c_str(), db_password.c_str());
    con->setSchema(db_schema.c_str());
    stmt = con->createStatement();
    printf("DATABASE: Connected to database... OK \n");
    return true;
  }
  catch (sql::SQLException &e)
  {
    std::cout << "# ERR: SQLException in " << __FILE__;
    std::cout  << "(" << __FUNCTION__ << ") on line " << __LINE__ << std::endl;
    std::cout  << "# ERR: " << e.what();
    std::cout  << " (MySQL error code: " << e.getErrorCode();
    std::cout  << ", SQLState: " << e.getSQLState() << " )" << std::endl;
    return false;
  }
}

So when i receive a request for example to list the userInfo in the userInfo request class i call the global pointer for the database class like this:

conDataBase->GetUserInfo(// the parameters);

Inside the GetUserInfo() i build my query like this:

res = stmt->executeQuery(query);

Its works but my real doubt is: Its is necessary to delete the pointer from mysqlconnector ( res, pstmt, con, etc )?. I'm scary about memory leaks in future. I'm only delete the pointers when the program exits but it is a real time program reason why he is not expected to be finished. If i delete the pointer in each query, insert etc (like the mysqlconnector examples do) in next time i have segmentation fault because when i run the program in first time i create the database pointers con, res, etc, so i cannot delete these pointers in each database operation because if i do this, in next time the pointers are deleted and i dont have access to him and its result in segmentation fault. Whats is the solution in these case to prevent memory leaks in future?

Answer 1

For such cases you can write a connectionManager class. It can be used to provide api's for :

1- creating and maintaining connection pool ,

2- getConnection api to get a connection instance from the pool,

3- a release connection api to put the connection instance back into opened connection's pool,

4- you should be using stl containers to store opened connections, etc